The use of MRI diagnostics in orthognathic surgery: prevalence of TMJ pathologies in Angle Class I, II, III patients.

AIM: Occasionally, undesirable post-surgical symptoms of temporomandibular disorder (TMD) and pain have been observed. The aim of this paper is to show how often and to which degree TMJ pathologies occur in orthognathic surgery candidates before surgery, making it recommendable to consider these TMJ pathologies during treatment planning.

PATIENTS AND METHODS: Between 2002 and 2004, Magnetic Resonance Imaging (MRI) of the TMJ were made in 58 randomly chosen orthognathic surgery patients. 69% of the patients were female, 31% were male. Age averaged 31.6 years (16-61 years). Gender and malocclusion (Class I, II and III) were looked at during analysis of the data (n = 58 patients, n = 116 TMJs). MRI scans were made at the beginning of treatment. We wanted to investigate the TMJ condition before surgery.

RESULTS: The largest patients group of this study were the female Class II patients (n = 25). Most patients displayed an Angle Class II (53.4%). The Class III patients followed (32.8%). A Class I molar relationship was found in 13.8% of the studied patients. A similar distribution could be observed in the parameters we studied: 1. condyle (position, degeneration), 2. disc (position, degeneration, prolapse and reduction). 76% of the TMJs (66.7%) showed dorsocranial condylar displacement. 26 of the 114 studied condyles (22.8%) were dorsally displaced. 108 of the studied joints (94.7%) showed condylar displacement. In 31 TMJs (28,4%) we found moderate, in 25 joints (22.9%) severe and in 26 joints (23.9%) we observed slight condylar degeneration. Most discs were displaced ventrally (31%). 22 of the studied 113 discs (19.5%) were displaced medially. 93% of the studied discs were not positioned correctly. 58 of the studied discs (58.6%) displayed flattening, in 8 (8%) we observed both flattening and disc adhesions. Two each of the studied TMJs had discs with perforations and adhesions or only perforations. In 57 (50.4%) of the studied discs we observed partial disc prolapse. Disc prolapse was total in 42.5% (n = 48 TMJs) of the TMJs. Eight TMJs (7%) of the 113 TMJs we analyzed showed no disc prolapse. Disc reduction was total in 71 (62.8%) of the studied TMJs. 15% (n = 17 TMJs) showed a partially reduced disc. 25 (22.1%) of the studied joints showed no disc reduction.

CONCLUSION: Apparently, MRI scans of the TMJ are necessary in almost all potential orthognathic surgery patients to achieve optimal surgical results. Female Class II patients recruited the largest patient group among the studied collective. It is this group that deserves the greatest caution before and after surgery (TMJ pathologies!). In patients with jaw discrepancies, a TMJ examination should be made prior to surgery in order to be able to include the condition of the TMJs in the planning of treatment. This examination best includes Magnetic Resonance Imaging (MRI) and Manual Functional Analysis (MFA).